This invention relates generally to magnetic disk drives and, more particularly, to suppressing seek noise and mechanical residual vibration in magnetic disk devices by eliminating certain seek spans.
Recently, there is an increasing demand for quieter magnetic disk drives in addition to conventional demands for lower price, higher storage capacity, higher access speed, and higher reliability. It is therefore desirable to reduce noise, residual vibration, and the like during random access operation. Conventionally, noise during random access operation is suppressed by such methods as thickening the cover of the magnetic disk drive and adding sound absorbing material. Meanwhile, a method for raising access speed is proposed in Japanese Patent Laid-Open No. 2001-14111. In this method, before tagged random access commands are executed, the command execution order is rearranged so as to more efficiently execute the tagged commands.
In addition, Japanese Patent Laid-Open No. 11-96700 describes a technique in which execution of a large-span seek operation is inserted to prevent external force from fluctuating when short-span seek operations are successively executed (FIG. 1).
In a magnetic disk drive according to the above-mentioned patent, before tagged random access commands are executed, the command execution order is optimized or rearranged so as to more efficiently execute the tagged commands. However, although this may bring about improvement in access performance, there is a possibility that specific seek spans corresponding to characteristic frequencies of the magnetic disk drive may induce resonance phenomena, resulting in such problems as increased operation noise and deteriorated positioning accuracy of the magnetic head due to residual mechanical vibration.